The present invention relates generally to fluid flow systems, and more particularly to a controllable fluid flow system for regulating the flow of air through a ventilation system.
Ventilation systems control the temperature and quality of air in an enclosed area such as a building. This is typically achieved by heating or cooling air by a centralized air conditioning unit then forcing the thermally conditioned air through a plurality of interconnected air carriers leading to various sections of the building. Ideally, the air carriers or ducts are configured and arranged to allow uniform distribution of forced air to maintain a desirable temperature setting throughout different areas of the building.
A properly balanced ventilation system results in lower operating costs and significant utilities conservation. However, due to structural restrictions, the air ducts must be bent and re-routed in order to reach the various areas of the building. Such deviations cause unpredictable flow impedance through the air ducts, thereby resulting in disparities in the optimal temperature level in various zones of the building.
Aside from the temperature imbalances caused by non-uniform distribution of thermally conditioned air, it may be required to individually control the temperature in various areas of a building. In modem buildings having various zones designed for variable functions and changing occupancy, it may be desirable to maintain a distinct temperature level in different zones. The conventional single source ventilation system connected to a centralized duct distribution network is not capable to provide variable flow impedance in different areas of the building.
One way of addressing the foregoing problems is to provide separate ventilation systems for individual areas of the building. Such solution is not economically feasible and requires extensive duct installation and isolation. Furthermore, the installation of such system results in waste of real estate dedicated to the individual ventilation systems.
Another possible solution to maintain desirable temperature balance in various parts of a building is to regulate the amount of forced air released from the ducts. Conventional ventilation systems often employ adjustable dampers incorporated into the exhaust end of air ducts to control the amount of forced air distributed to an area of the building. These dampers regulate the amount of air flowing through the respective ducts by adjusting the degree that the dampers open. The dampers may be manually adjusted to regulate the air flow, gravity or air flow actuated, or could be actuated by means of electric motors or solenoid actuators. See for example U.S. Pat. No. 5,433,660 issued Jul. 18, 1995 to Ohba. However, there are a number of drawbacks associated with the prior systems. Manual adjustment of the dampers is cumbersome since the ducts are typically located in inaccessible areas. Although the motor operated dampers can be thermostatically controlled, they are not an optimal implementation of a flow regulation system as they are expensive, consume energy, and are prone to breaking down. Moreover, it may be difficult to find a replacement motor if the motor has been discontinued. As for the solenoid actuators, they generally operate in cooperation with gravity, air pressure or the bias of a spring to actuate the damper. This is quite inefficient as the damper""s action is not in response to changes in the temperature.
The present invention provides a symmetrical magnetically controlled flow system for regulating the flow of thermally conditioned air in a multiduct ventilation system which addresses the shortcomings associated with known systems.
The present invention arises from the realization that the existing adjustable dampers used for regulating the distribution of thermally conditioned air to various zones of a building are inefficient, difficult to adjust and expensive to maintain and operate. To alleviate these problems, the present invention provides a magnetically controlled flap incorporated in the exhaust end of an air duct having a magnetically attractive member located thereon. Two coils with magnetizable cores are mounted inside the air duct and positioned so as to cooperatively bias the magnetically attractive member when the flap is in either a closed or an open position. By energizing the coils, the magnetically attractive member becomes attracted to the magnetizable cores in either coil, thereby actuating the flap between the closed and open positions. The coils"" action may be managed by a controller sensitive to changes in the ambient temperature.
In a first aspect, the present invention provides a device for controlling the flow of a fluid through a flow passage defined by a conduit, including a flap for mounting in the conduit for movement between a first position and a second position, the flap restricting the flow of the fluid in the conduit more in the second position than in the first position. A magnet is mounted on the flap. The device further includes a stationary first electromagnet for acting on the magnet to bias the flap towards the first position when energized and a stationary second electromagnet for acting on the magnet to bias the flap towards the second position when energized
In another aspect, the present invention provides a magnetically controlled flow system comprising: (a) a conduit for carrying the flow of thermally conditioned fluid to an enclosure; (b) blocking means movably disposed in the conduit and are selectively operable in an open position allowing flow of fluid, or a closed position blocking the flow of fluid therethrough; (c) a magnetically attractive member disposed on the blocking means; (d) a first latch means for acting on the magnetically attractive means to cause the blocking means to move to an open position; and (d) a second latch means for acting on the magnetically attractive means to cause the blocking means to move to a closed position.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.